Based on the relief I experienced after bilateral hip replacement, and my sister-in-law's recent success with both knees replaced at age 64, I suggest you consider the surgery as soon as your ortho advises, followed by faithful PT to recover. I am comparing our results to the struggles I have seen in people who waited longer and were therefore more disabled by long-term pain or had surgery when they were quite a bit older.

By the way, my Mom had her knee replaced before she was 60 and continued an active life until 80, it was still in fine shape when she passed away at 84, so they do last a long time compared to early implants that were prone to wear out.
Sue